The first one occurred 19 days into the new year when a man used an ax to kill four family members including his infant daughter. Five months later, 12 people were killed in a workplace shooting in Virginia. Twenty-two more died at a Walmart in El Paso in August.
A database compiled by The Associated Press, USA Today and Northeastern University shows that there were more mass killings in 2019 than any year dating back to at least the 1970s, punctuated by a chilling succession of deadly rampages during the summer.
In all, there were 41 mass killings, defined as when four or more people are killed excluding the perpetrator. Of those, 33 were mass shootings. More than 210 people were killed.
Most of the mass killings barely became national news, failing to resonate among the general public because they didn't spill into public places like massacres in El Paso and Odessa, Texas; Dayton, Ohio; Virginia Beach, Virginia; and Jersey City, New Jersey.
The majority of the killings involved people who knew each other - family disputes, drug or gang violence or people with beefs that directed their anger at co-workers or relatives.
In many cases, what set off the perpetrator remains a mystery.
That's the case with the very first mass killing of 2019, when a 42-year-old man took an ax and stabbed to death his mother, stepfather, girlfriend and 9-month-old daughter in Clackamas County, Oregon. Two others, a roommate and an 8-year-old girl managed to escape; the rampage ended when responding police fatally shot the killer.